Abstract

One of the factors in the decision to extend operating licenses of the United States pressurized reactor reactors (PWRs) is complying with the Pressurized Thermal Shock (PTS) rule, 10CFR50.61, promulgated in 1985. Currently there are ten plants in the United State whose life extension could be affected by the PTS rule. In 1998 the US Nuclear Regulatory Commission (NRC) lunched a PTS re-evaluation project aiming not only reassessing the PTS screening criteria but also taking all important uncertainties into account explicitly. Four PWRs are included in the study: Oconee-1, Beaver Valley-1, Palisades, and Claver Cliffs-1.